Carver Crimson 275 Review (Tube Amp)

[restorer-john]

I may have missed this... why is it a safety hazard?

Where to start?

The IEC three pin socket is not chassis earthed. You cannot fit one and not earth it.

Alternatively, the wiring is not up to double insulated standard and unsafe (no insulation/poor soldering/chassis gnd resistor to neutral). So we have a metal chassis device that appears to have a earth pin, but is not earthed and not properly or insulated constructed. It fails on both counts.

Look at the active power switch soldering. It is disgusting. As is the mains fuse holder soldering- no quality work, insulation etc.

What is holding the power supply in place? A bit of sticky black foam tape?

 

[abdo123]

And where would a layperson see this "safety ground"?

It’s visible in the pictures Amir took, right at the mains power socket.

 

[restorer-john]

And where would a layperson see this "safety ground"?

They would see a correctly terminated green/yellow wire going from the centre pin of the IEC 3 pin socket to an eyelet, screw, spring washer, washer and two nuts directly physically and electrically mounted to the chassis.

There is a resistor connecting the neutral to the chassis. Something done back in the bad old days.

 

[traderitch]

Where to start?

The IEC three pin socket is not chassis earthed. You cannot fit one and not earth it.

The wiring is not up to double insulated standard and unsafe (no insulation/poor soldering/chassis gnd resistor to neutral). So we have a metal chassis device that appears to have a earth pin, but is not earthed and not properly insulated constructed.

Look at the active power switch soldering. It is disgusting. As is the mains fuse holder soldering- no quality work, insulation etc.

What is holding the power supply in place? A bit of sticky black foam tape?

I really appreciate your response. I do not believe one should be flippant in response to an inquiry related to safety.

As far as IEC three pin sockets not being chassis earthed. My personal observation of modern audio equipment is the third pin is not being used as you can see in in this Marantz AV8805 (reviewed here in February 2019)

 

[NTK]

I may have missed this... why is it a safety hazard?

OK. I'll bite. This is a crop of a picture from post #1. You can see that there are wires carrying 120 VAC soldered to tabs of the switch, PCB, fuse holder, etc. If one of them came loose, it may short 120 VAC to the chassis. This is a single point failure that can cause the chassis to become a lethal hazard, and is a huge no-no.

 

[SIY]

And where would a layperson see this "safety ground"?

Here's a good overview of basic electrical product safety. Selling products that do not conform to basic safety standards is straight out unethical.

 

[SIY]

I really appreciate your response. I do not believe one should be flippant in response to an inquiry related to safety.

As far as IEC three pin sockets not being chassis earthed. My personal observation of modern audio equipment is the third pin is not being used as you can see in in this Marantz AV8805 (reviewed here in February 2019)

This isn't a Class I device and that's not a three pin IEC. Note the symbol.

 

[BlackTalon]

It depends - are we talking 300B bottledick or 12AX7 bottledick?

Here is another guide. Definitely nothing to be ashamed of...

 

[traderitch]

View attachment 179513

This isn't a Class I device and that's not a three pin IEC. Note the symbol.

I appreciate the response - the page count of this thread would be cut in half and the informative content would be much more beneficial had people been less emotional and more substantive - like you

 

[BlackTalon]

Neat. Thanks. Will pick one up. Being a woodworker I have moisture sensor but has pins.

Delmhorst capacitance meters (with pins) are pretty much the gold standard. Pinless only if you really, really, really do not want small holes in the material that need to be skimmed over.

 

[restorer-john]

As far as IEC three pin sockets not being chassis earthed. My personal observation of modern audio equipment is the third pin is not being used as you can see in in this Marantz AV8805 (reviewed here in February 2019)

It is a Class ii device and is fitted (correctly) with a two pin IEC and the Double insulated symbol. Look at your own picture:

 

[Thermionics]

Thanks for the measurement Amir!

Well what to say. If you are now going tube way see also relation to price, I think this seems interesting:
(think of service, possible recap and so on when considering a purchase)

Review and Measurements of Dynaco ST 70

This is a review and detailed measurements of the vintage Dynakit Dynaco Stereo 70. It is on kind loan from a member who bought it used online and repaired it. Previous owner hand upgraded it but could not get it working. Given that it is 60 years old, one can forgive the rust and dust...

audiosciencereview.com

This is just as interesting, see attached picture:

If "Tube Sound" Is a Myth, Why Tubes?

Just curious, what is your sureness based on? I do wish a card saying "amp designer" would make me technically and factually infallible, but unfortunately it doesn't seem to work that way (just witness some hot-shot "amp designers" spewing absolute BS). Measurements, experience, longevity in the...

audiosciencereview.com

Advantage Dynaco ST 70. It is so famous. There is a demand. Just find out where the used price is usually in the country you live in. Buy and sell for more or less the same price. So you then you have tested on a tube amp. Or you may keep it, what do I know. The taste is different and varies.

Or build your own...

 

[Thermionics]

“Sideshow” is the word that comes to mind.

Unlike many (older) folks I don’t have warm fuzzies about the Carver name. My first exposure was the Sunfire “True Subwoofer,” an amusical thing that got loud pretty low in a small cabinet but otherwise had no virtues. The Carver “ribbon” speaker Circuit City sold (long planar, maybe downfiring woofer) sounded very disjointed. He may have been right on fact with the Stereophile amp challenge thing but his approach belonged in a circus ring. So I’m not shocked by the all-show nature of this amp.

Sadly, I was thinking of another kind of show upon seeing those measurements. When I heard about the new Bob Carver tube amps, I was initially interested, glad I was too poor to indulge.

 

[traderitch]

It is a Class ii device and is fitted (correctly) with a two pin IEC and the Double insulated symbol. Look at your own picture:
View attachment 179514

Restorer-john,

I was seeking information - had I recognized the difference in 'my own picture' I would not have inquired and posted.
It is difficult to interpret inflection in the written word so I will give you the benefit of the doubt that your intent was to be helpful.

 

[Thunder22]

Restorer-john,

I was seeking information - had I recognized the difference in 'my own picture' I would not have inquired and posted.
It is difficult to interpret inflection in the written word so I will give you the benefit of the doubt that your intent was to be helpful.

I will give you the benefit of the doubt that your intent is not to be a troll.

 

[restorer-john]

Restorer-john,

I was seeking information - had I recognized the difference in 'my own picture' I would not have inquired and posted.
It is difficult to interpret inflection in the written word so I will give you the benefit of the doubt that your intent was to be helpful.

You said:

As far as IEC three pin sockets not being chassis earthed. My personal observation of modern audio equipment is the third pin is not being used as you can see in in this Marantz AV8805 (reviewed here in February 2019)

And you post a picture of a two pin IEC socket in support of your 'personal observation'. What do you expect?

You will not see a 3 pin IEC socket on any major brand product where it is double insulated (class ii) or not actually earthed. It is illegal.

 

[Greg P]

I've said this in another forum, but I'll repeat it here. IMO, this was a "concept" amp. The design itself isn't sloppy (even if the build is). Take a small OPT, use a hefty amount of compensation and a few technical tricks, run the tubes cool, cool, cool, get some good peak power in the midrange, and maybe some harmonic doubling (or something like that) in the lows. 15 watts continuous suffices for a lot of people.
........
ETA: I guess it turned out to be more of an Edsel than a Cobra, but hell, a lot of people liked their Edsels!

The Edsel was a very decent and well-built car for its time. I think that the Yugo is the better comparison....

 

[AudioSceptic]

Neither would be that wonderful, as in the case of the Quad, PW explained in at least one interview that his work in 'listening' to his earlier designs was to try to 'tune' distortions away from our most sensitive frequencies so hopefully they wouldn't be noticed. I have a set of (Glenn Croft) rebuilt Quad II's here and into more lively speakers than the 'Thunderboxes' I current need to use, they sound absolutely 'glorious' I have to say (so does the good-example 303 here, but we're talking valves so shan't go further). The TL12's I borrowed were really odd. Connect to a different speaker and they sounded 'odd' for half an hour, after which they seemed stable enough. Go back to the original speakers and these too sounded less good for half an hour. No idea what was going on electrically, but at the time I found it repeatable, so *hopefully* not merely 'sighted shenanigans.'

My now older Brit perspective wants some of the better E.A.R amps tested and for the subjective based forums, the ever recommended Leben boxes which hide the valves behind a dated looking front panel. PrimaLuna (another bad measuring but popular unintentional? equaliser-amp) seems to have been amply covered in Stereophile.

Thanks for that. Another valve fave (for reviewers: I"ve never heard one) was the Michaelson & Austin TVA. I did hear a Beard valve amp somewhere once and it sounded not bad at all, FWIW.

 

[PeteL]

This amp makes objective claims that is appealing to people as far was power. No doubt there is good commonality between people who buy it and our readership.

Possible, but anyway you look at it, after these measurments there won't be any sales from this community, regardless of what they can come up with to defend them. Maybe they simply have nothing to argue against? I believe than in these cases of such poorness, you just wish as a manufacturer for the thread to gain the least interest possible, and the enthousiasm for it to fade. You don't come here and fuel the fire. I am pretty certain that Mr Clark thing is some guy going rogue, Not any communications on behalf of Bob Carver's company.

 

[traderitch]

You said:


And you post a picture of a two pin IEC socket in support of your 'personal observation'. What do you expect?

You will not see a 3 pin IEC socket on any major brand product where it is double insulated (class ii) or not actually earthed. It is illegal.

I had hoped your response would have only included the second sentence.
That would have been sufficient.